Investments and Fair Value Measurements (Details) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014		Dec. 31, 2013
Cash, cash equivalents and investments [Abstract]
Cash	$ 25,662,000			$ 22,337,000
Cash equivalents [Abstract]
Certificates of deposit, amortized cost	7,623,000	[1]		6,454,000	[1]
Certificates of deposit, gross unrealized gain	0	[1]		0	[1]
Certificates of deposit, gross unrealized loss	0	[1]		0	[1]
Certificates of deposit, fair value	7,623,000	[1]		6,454,000	[1]
Money market fund	0			23,000
Total cash and cash equivalents	33,285,000		22,760,000	28,814,000		24,961,000
Amortized Cost	47,076,000			48,267,000
Gross Unrealized Gain	449,000			712,000
Gross Unrealized (Loss)	(38,000)			(42,000)
Fair Value	47,487,000			48,937,000
Contractual maturities on investments, amortized cost basis [Abstract]
Due within 1 year	3,144,000			11,631,000
Due after 1 through 5 years	10,647,000			7,822,000
Investments, amortized cost	13,791,000			19,453,000
Contractual maturities on investments, fair value basis [Abstract]
Due within 1 year	3,590,000			12,340,000
Due after 1 through 5 years	10,612,000			7,783,000
Investments, fair value	14,202,000			20,123,000
Proceeds from sales of available-for-sale investments	387,000		0
Gross realized gains from sales of available-for-sale investments	367,000		0
Unrealized gain, net of tax	448,000.0
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	11,329,000			8,262,000
Gross unrealized loss, in loss position less than twelve months	(38,000)			(40,000)
Fair value, in loss position greater than twelve months	480,000			4,309,000
Gross unrealized loss, in loss position greater than twelve months	0			(2,000)
Fair value, total in loss position	11,809,000			12,571,000
Gross unrealized loss, total in loss position	(38,000)			(42,000)
Minority Investments [Abstract]
Minority investments in unconsolidated privately-held companies	200,000			200,000
Other Assets [Member]
Minority Investments [Abstract]
Investments in privately-held companies	12,500,000			12,100,000
Minority investments in unconsolidated privately-held companies	200,000			200,000
Certificates of Deposit [Member]
Cash equivalents [Abstract]
Amortized Cost	6,425,000	[2]		10,195,000	[2]
Gross Unrealized Gain	1,000	[2]		1,000	[2]
Gross Unrealized (Loss)	(7,000)	[2]		(13,000)	[2]
Fair Value	6,419,000	[2]		10,183,000	[2]
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	4,018,000			4,492,000
Gross unrealized loss, in loss position less than twelve months	(7,000)			(13,000)
Fair value, in loss position greater than twelve months	480,000			0
Gross unrealized loss, in loss position greater than twelve months	0			0
Fair value, total in loss position	4,498,000			4,492,000
Gross unrealized loss, total in loss position	(7,000)			(13,000)
Corporate Bonds [Member]
Cash equivalents [Abstract]
Amortized Cost	7,342,000			9,214,000
Gross Unrealized Gain	0			1,000
Gross Unrealized (Loss)	(31,000)			(29,000)
Fair Value	7,311,000			9,186,000
Summary of fair value and gross unrealized losses related to available-for-sale securities [Abstract]
Fair value, in loss position less than twelve months	7,311,000			3,770,000
Gross unrealized loss, in loss position less than twelve months	(31,000)			(27,000)
Fair value, in loss position greater than twelve months	0			4,309,000
Gross unrealized loss, in loss position greater than twelve months	0			(2,000)
Fair value, total in loss position	7,311,000			8,079,000
Gross unrealized loss, total in loss position	(31,000)			(29,000)
Corporate Equity Security [Member]
Cash equivalents [Abstract]
Amortized Cost	24,000			44,000
Gross Unrealized Gain	448,000			710,000
Gross Unrealized (Loss)	0			0
Fair Value	472,000			754,000
Total Investments [Member]
Cash equivalents [Abstract]
Amortized Cost	13,791,000			19,453,000
Gross Unrealized Gain	449,000			712,000
Gross Unrealized (Loss)	(38,000)			(42,000)
Fair Value	$ 14,202,000			$ 20,123,000

[1] Certificate of deposit with original maturities of less than 90 days.

[2] Certificate of deposit with original maturities of more than 90 days.